When we bought our 120 year old Edwardian semi 5 years ago, it was a state...but then you could tell that walking through on the viewings. As PP mention, it really depends on how the property has been maintained.
Our vendor had owned the house for 32 years, and the fuse box looked like it had last been changed 50 years ago! There was an open gas meter in one of the rooms (which we had to pay the Centrica parent company to come and move as it was unsafe), and the boiler was in a bedroom.
It wasn't initially priced accordingly, however the amount of work recommended became crystal clear when the survey came through, and we were able to negotiate further. We did the majority of improvements to bring it up to modern standards (though far from everything in the structural report), and now have a beautiful home with high ceilings and large rooms which we're about to sell.
Surveyors have to include a fair amount of whatifs, so I'd make your judgement based on what realistically needs to be done to modernise/improve, and what you can live with.
Our next house will be a 1930's semi which when I hear talk about them consider to be reasonably modern, but thinking about it, are nearly 100 years old. They tend to be solid, sturdy brick built houses, with decent room sizes (other than the box room!). They don't tend to be money pits, unless there's lots of botched DIY to unpick.